You will find the corresponding option inside:
Dashboard >> Appearance >> Customize >> BuddyPress Nouveau >> Member Navigation.
Here you will get the following options to customize the navigation menu for members. In the preview window, navigate to a user to preview your changes.
- Display the member navigation vertically.

- Use tab styling for the primary nav.

- Use tab styling for the secondary nav.

- It also allows you to drag each possible member’s navigation item into a preferable order.

